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111.
N. Dupr J. Gaubicher T. Le Mercier G. Wallez J. Angenault M. Quarton 《Solid State Ionics》2001,140(3-4):209-221
A detailed electrochemical study of Li insertion in the -form of VOPO4 and the optimization of the cycling performance are presented. The redox process occurs in one step close to 3.76 V, along with a phase transition. In order to improve the intercalation kinetics, the electronic conductivity was optimized by introducing a mixed valency, and the ionic conductivity was favored by introducing ‘pillaring’ molecules or ions in the interlayer space. In this way, the electrochemical behaviors of -VOPO4·2H2O, -NaxVOPO4, -KxVOPO4 and -MgxVOPO4 (0≤x≤1) have been studied: the hydrate compound shows a good specific capacity (100 mA h/g at a C/5 regime), but a poor cyclability was mainly because of water oxidation. The inserted large alkaline ions improved the cyclability up to 80 cycles (Na+) or over 100 cycles (K+). Enhancements of the VOPO4 specific capacity have been obtained as well by mechanical ball-millings. 相似文献
112.
This paper deals with the prediction of the macroscopic behavior of a multiphase elastic–viscoplastic material. The proposed homogenization schemes are based on an interaction law postulated by Molinari et al. [Molinari, A., Ahzi, S., Kouddane, R. 1997. On the self-consistent modelling of elastic–plastic behavior of polycrystals. Mech. Mater., 26, 43–62]. Self-consistent schemes are developed to describe the behavior of disordered aggregates. The Mori-Tanaka approach is used to capture the behavior of composite materials, where one phase can be clearly identified as the matrix. The proposed schemes are developed within a general framework where compressible elasticity and anisotropy of the materials are taken into account. Inclusions can have various shapes and orientations. Illustrations of the homogenization procedure are given for a two-phase composite materials. Comparisons between results of the literature and predictions based on the interaction law are performed and have demonstrated the efficiency of the proposed homogenization schemes. 相似文献
113.
Ahmed Oueslati Imen Abdelhedi Régis Mercier Eric Drockenmuller Hatem Ben Romdhane 《Journal of polymer science. Part A, Polymer chemistry》2013,51(21):4650-4656
Photoresponsive polyamides containing main‐chain pentamethylated norbornadiene (NBD) moieties are obtained in quantitative yields via the Yamazaki–Higashi reaction between a pentamethylated NBD dicarboxylic acid and a series of aromatic diamines. Chemical structures are confirmed by 1H and 13C NMR and weight average molar masses measured by SEC are in the range of 21,500–28,600 g mol?1 with chain dispersities close to 2. Physical properties are investigated by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis, and viscosimetry. All obtained polyamides are amorphous with glass transition temperatures ranging from 68 to 124 °C. They are soluble at room temperature in common organic solvents and exhibit good thermal stabilities with Td10 values ranging from 175 to 276 °C. The photochemical isomerization of the NBD moiety into quadricyclane (QC) is studied by UV/vis spectroscopy after sunlight irradiation of polymer films. For all polyamides, a first‐order kinetic rate is observed for the conversion of NBD to QC. The thermal release of the stored energy associated to the reverse transformation of QC groups into NBD ones is about 90–95 kJ mol?1 as measured by DSC of the irradiated polymer films. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4650–4656 相似文献
114.
115.
The present study investigates, through measurements in a 2D wave tank, the velocity fields of a plunging breaking wave impinging
on a structure. As the wave breaks and overtops the structure, so-called green water is generated. The flow becomes multi-phased
and chaotic as a large aerated region is formed in the flow in the vicinity of the structure while water runs up onto the
structure. In this study, particle image velocimetry (PIV) and its derivative, bubble image velocimetry (BIV), were employed
to measure the velocity field in front and on top of the structure. Mean and turbulence properties were obtained through ensemble
averaging repeated tests. The dominant and maximum velocity of the breaking wave and associated green water are discussed
for the three distinct phases of the impingement–runup–overtopping sequence. Initially the flow is mainly horizontal right
before the breaking wave impinges on the structure. The flow then becomes primarily vertical and rushes upward along the front
wall of the structure right after the impingement. Subsequently, the flow becomes mainly horizontal on top of the structure
as the remaining momentum in the wave crest carries the green water through. The distribution of the green water velocity
along the top of the structure has a nonlinear profile and the maximum velocity occurs near the front of the fast moving water.
Using the measured data and applying dimensional analysis, a similarity profile for the green water flow on top of the structure
was obtained, and a prediction equation was formulated. The prediction equation may be used to predict the green water velocity
caused by extreme waves in a hurricane. 相似文献
116.
Marwitz AJ Dutton JL Mercier LG Piers WE 《Journal of the American Chemical Society》2011,133(26):10026-10029
A chemically competent indirect pathway for the activation of dihydrogen by the nonmetal Lewis acid/Lewis base pair (t)Bu(3)P/B(C(6)F(5))(3) is described. The reaction between (t)Bu(3)P and B(C(6)F(5))(3) produces [(t)Bu(3)PH](+)[FB(C(6)F(5))(3)](-) and the known phosphinoborane p-(t)Bu(2)P-C(6)F(4)-B(C(6)F(5))(2) (1-(t)Bu) with elimination of isobutylene. At 1:1 stoichiometry, 1-(t)Bu is produced rapidly in detectable quantities and can act as a catalyst for the formation of [(t)Bu(3)PH](+)[HB(C(6)F(5))(3)](-) from (t)Bu(3)P and B(C(6)F(5))(3) in the presence of H(2). The extent to which this indirect path competes with the direct path is explored. 相似文献
117.
François Nief François Mercier François Mathey 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Whereas the parent phosphine is a highly poisonous, easily oxidized gas, a phosphine complex such as W(CO)5PH3 is much easier to handle, as this complex is an air stable white solid. 相似文献
118.
William Clegg Ross W. Harrington Lauren G. Mercier Warren E. Piers 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(4):436-438
The molecule of the title silepine compound, C28H24Si, lies on a crystallographic general position but has almost exact mirror symmetry. The seven‐membered silepine ring has a boat conformation, with a fold angle of 99.99 (9)° between the C—C=C—C stern and the C—Si—C prow. The planes of the phenyl substituents are rotated by 32.23 (6) and 31.80 (7)° out of the planes of the respective fused benzene rings. Similar folded conformations are found for other dibenzo[b,f]silepines, while analogous dibenzo[b,f]borepines, in which the B atom can participate in conjugation, have a more flattened heterocyclic ring. 相似文献
119.
Leblanc N Mercier N Zorina L Simonov S Auban-Senzier P Pasquier C 《Journal of the American Chemical Society》2011,133(38):14924-14927
The search for hybrid organic-inorganic materials, which have the great advantage that they can be synthesized at moderate temperature (T < 200 °C), remains a great challenge in the field of ferroelectrics. Here, a room-temperature ferroelectric material with interesting characteristics, (MV)[BiI(3)Cl(2)] (MV(2+) = methylviologen), is reported. Its structure is based on polar inorganic chains resulting from a remarkable Cl/I segregation induced by methylviologen entities, which coincide with the fourfold polar axis of the tetragonal structure. Of great importance is that this room-temperature hybrid ferroelectric displays a clear electrical hysteresis loop with a large spontaneous polarization (>15 μC·cm(-2)). 相似文献
120.
Image texture is a neighborhood information which is time consuming to analyze by computer. Optical processing can be used as a preprocessor to reveal some of the texture information in parallel on the whole image before classification of the preprocessed image by computer. Pseudocoloring allows an easy discrimination of texture information. A specialized binary black and white mask is introduced which selects at one particular wavelength one peak of the diffracted power spectrum of each texture considered. The method is applicable to textures showing some periodicity. The resolution, selectivity and difficulties of the method are described qualitatively and an experimental example including a problem of partial cross talk between different textures is presented. 相似文献